Mobile radio communications device for closed subscriber group management

ABSTRACT

The present invention provides for a mobile radio communications device, and related method of operation, arranged for closed subscriber group selection and for the storage of closed subscriber group information in the device, the stored information including information configured as a whitelist of closed subscriber group identities delivered between non-access-stratum layer and access-stratum layer within the device, and the device being further arranged to remove a previous user-selected closed subscriber group identity from the whitelist responsive to the device connecting to a cell is different from that identified by the previous user-selected closed subscriber group identity, and which different cell can comprise for example a non-CSG cell.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is continuation application of U.S. patent applicationSer. No. 13/805,603 filed Feb. 12, 2013, which is a National Stage ofInternational Application No. PCT/JP2011/064613 filed Jun. 20, 2011,which claims priority from United Kingdom Patent Application No.1010393.5, filed Jun. 21, 2010, the contents of all of which areincorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a mobile radio communications device,and related method of operation, arranged particularly for ClosedSubscriber Group (CSG) functionality.

BACKGROUND ART

The functionality afforded mobile radio communications devices such ascell phone handsets has been increasingly defined by reference to theThird Generation Partnership Project (3GPP) proposals and standards andwhich has focused most recently upon ongoing improvements to theUniversal Mobile Telecommunications System (UMTS) such as the LongTerminal Evolution (LTE) ongoing improvement thereto. The presentinvention relates in particular to 3GPP LTE compatible wirelesscommunication systems and in particular E-UTRAN resources which canemploy relatively small building-focused cells such as so-calledfemtocells.

The User Equipment (UE) forming the mobile terminal devices found forexample within UMTS systems can benefit from increasingly diversefunctionality. One such feature, which can prove particularlyadvantageous within a femtocell environment, is CSG functionality.

Within a CSG arrangement, a group of one or more cells, e-NodeBs or basestations or otherwise, are provided for which access is restricted to alimited group of one or more users. The members of that restricted groupcan benefit from their access to the sub group of cells due to thespecific/improved services available via those restricted cells.

A CSG is commonly administered by a network operator wishing to reserveaccess to certain cells within their mobile network. In this manner, anidentifier, such as a CSG ID is commonly broadcast by each restrictedcell, by way of its system information. Each UE operating within thenetwork may only select such a restricted cell if the broadcast CSG IDis already found within a list stored within the UE. Any appropriateconfiguration of such list or lists, can be provided and they cancommonly comprise a so-called “operator controlled CSG list” and/or andan “allowed CSG list”. Such lists are commonly stored within the USIM ofthe UE.

A hybrid CSG cell can also be provided that comprises a CSG cell foraccess by permitted users, by way of operator subscription, but also bysome users that do not have an operator subscription.

Automatic selection can then be made responsive to a match between theCSG ID broadcast by a restricted cell, and the content of the “operatorcontrolled” and “allowed” lists stored in the UE. Alternatively, or inaddition, the user can manually search for CSG cells of potentialinterest and, once found, request the UE to attempt to register to arestricted cell even though the CSG ID is neither within its “operatorcontrolled” or “allowed” CSG lists. In spite of such absence from thelists, should registration to the restricted cell prove successful, theCSG ID of that selected cell can then be added to the “allowed CSGlist”.

Thus, automatic and manual registration to the restricted cell ispossible.

Insofar as the selection of CSG IDs stored within the UE and, inparticular within the “operator controlled CSG list” can be determinedby the network operator, further control functionality is afforded theoperator insofar as the operator can selectively inhibit the use of theabove-mentioned “allowed CSG list”. Accordingly, although a manualselection process might have led to successful registration to arestricted cell, the aforementioned inhibition can be employed by theoperator such that the CSG ID of that cell is not subsequently added tothe “allowed CSG list” so as to inhibit subsequent automatic selectionof that cell.

Insofar as the user-controlled CSG list within the UE, i.e. theabove-mentioned “allowed CSG list”, can therefore be inhibited by thenetwork, disadvantageously limiting and potentially problematicscenarios can develop should the UE, by performing a manual CSGselection, attempt to move to a CSG cell whose identity is not foundwithin the “operator controlled CSG list”. That is, in further detail,if, for some reason, the radio signal quality derived from therestricted cell remains insufficient, a different cell which may not berestricted is likely to be selected by the UE. However, as and when theradio signal from the restricted cell improves, automatic reselection ofthat restricted cell will not be possible and the user will have toagain attempt manual selection of the CSG cell. As will be appreciated,the absence of the CSG ID from the “operator controlled CSG list”, andthe inhibiting of the “allowed CSG list” serves to prevent suchautomatic selection.

Yet further, if there are several restricted cells each having the sameCSG ID, which might be required to ensure proper coverage within acertain area, for example several rooms within a building accordinglyfemtocell arrangement, the other restricted cells will not be selectedautomatically. As the UE moves cells, even though the signal from theselected cell might again become too weak another related restrictedcell providing the appropriate service will not be automaticallyselected due, as noted above, to the absence of these CSG identifiedfrom the “operator controlled CSG list” and the inhibiting of the“allowed CSG list”.

In situations in which the restricted cells are likely to providespecific and/or such improved services, such scenarios are quite clearlydisadvantageously limited and repeated manual intervention is requiredeach time in an attempt to resume such services.

Various control and management arrangements for CSG scenarios are knownin the current art and one example comprises the subject matter ofUS-A-2010/0110945. This document discloses a system and method forproviding CSGs within a packet-based wireless communications system andrelates, in particular, to a manner in which CSG identities are handledwithin the UE for the performance of cell selections and reselections.

Illustrative of the nature of the problems and limitations found in theprior art, it is noted that the subject matter of US 2010/0110945 has nodisclosure nor suggestion as to how to handle CSGs that are not allowedin the whitelist due in particular to network operator inhibition.

Further, the signaling arrangement disclosed within this document isdisadvantageously limited.

DISCLOSURE OF INVENTION

The present invention seeks to provide a mobile radio communicationsdevice and related management method, employing CSG and which exhibitsadvantages over known such devices and methods.

According to a first aspect of the present invention, there is provideda mobile radio communications device arranged for closed subscribergroup selection and for the storage of closed subscriber groupinformation, the stored information including information configured asa white list of closed subscriber group identities delivered betweennon-access-stratum layer and access-stratum layer within the device, andthe device being further arranged to remove a previous user-selectedclosed subscriber group identity from the white list responsive to thedevice connecting to a cell is different from that identified by theprevious user-selected closed subscriber group identity.

The invention is advantageous in responding to network operatorinhibition within the whitelist and which leads to a requirement formanual selection. In particular, the invention facilitates this throughremoval of the “inhibited” CSG ID and such that manual selection willthen have to be pursued.

Compared with the current art therefore, the user can readily performmanual CSG selection.

Advantageously, the removal of the previous user-selected closedsubscriber group identity is responsive to the device connecting to anon-CSG cell or a CSG cell different from that identified by theprevious user-selected closed subscriber group identity.

Further, the white list can be under non-access stratum control andwherein no indication is provided to the access stratum as to whether auser-controlled closed subscriber group list is network-inhibited.

In this manner, the non-access stratum layer can notify the whitelist tothe access stratum layer once updated by the removal.

As an alternative of course, the method can include an access stratumcontrolled white list.

Preferably, the device can be arranged such that an indicator isprovided to the access stratum as whether a user-controlled closedsubscriber white list is network-inhibited. Also, responsive to thedevice connecting to a cell comprising a different closed subscribergroup identity, the aforesaid new identity can serve to supersede theremoved identity.

In a particular arrangement, the removal of a previous user-selectedclosed subscriber group identity occurs subsequent to network-inhibitionof an allowed closed subscriber group list within the device.

According to another aspect of the present invention, there is provideda method of managing closed subscriber group selection in a mobile radiocommunications device and including the step of storing closedsubscriber group information configured as a whitelist of closedsubscriber group identities to be delivered between a non-access stratumlayer and an access stratum layer within the mobile radio communicationsdevice, and removing a previous user-selected closed subscriber groupidentifier from the white list responsive to the device connecting to acell which is different from that identified by the previoususer-selected closed subscriber group identifier.

As with the device discussed above, the step of removal can responsiveto connection to a non-closed subscriber group cell or to a differentclosed subscriber group cell.

Also, the method can provide for non-access stratum control of the whitelist or access stratum-control of the white list.

Yet further, the removed user-selected closed subscriber groupidentifier can be superseded when the device connects to a cellcomprising a new closed subscriber group identifier.

The invention can also provide for a computer program, computer programproduct or computer readable medium, comprising instructions that carryout a method as defined above.

Also within the scope of the present invention is a mobilecommunications system including a mobile radio communications device asdefined above and a network device arranged to communicate closedsubscriber groups signaling with the mobile radio communications device.

As will therefore be appreciated, the present invention relates toimprovements for manual CSG selection in situations that arisesubsequent to inhibition of the “user controlled CSG list” within the UEby the network. As discussed, UMTS and LTE radio access systems andservices in particular can benefit from the present invention. Withinthe present invention the mobile radio communications device such as theUE, and the related mentioned method, can offer advantages in CSGselection through signaling achieved at non-access stratum and accessstratum levels through interaction with, generally, a single CSGidentity within, preferably volatile memory within the device. As willbe appreciated from the foregoing, and the detailed description thatfollows, a principal advantage of the present invention is that a usercan readily avoid a need to repeat a manual CSG selection procedure whenmoving between cells covered by the same CSG and non-CSG cells inparticular.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described further hereinafter, by way of example only,with reference to the accompanying drawings:

FIG. 1 is a schematic block diagram of a mobile radio communicationsdevice according to an embodiment of the present invention;

FIG. 2 is a signaling diagram arising in relation to one aspect of thepresent invention; and

FIG. 3 is a signaling diagram relating to signaling arising in relationto a further aspect of the present invention.

EMBODIMENTS FOR CARRYING OUT THE INVENTION

Turning first to FIG. 1, there is provided a schematic diagram of themobile radio communications device in the form of a cell phone handset10 having a signaling phase comprising a standard 10 and 12 andtransceiver circuitry 14 and while functional processing 16 and storage18 are also indicated.

The device also employs a USIM 20 for provision of the usualuser-related functionality and which in this illustrated embodiment, isarranged to include a storage location, preferably having a volatileelement, for storing both and “operator controlled CSG list” and an“allowed CSG list”. As discussed above, the “operator controlled CSGlist” can comprise a list of CSG IDs to-which the network operatorallows connection by the handset 10 whereas the “allowed CSG list” cancomprise a historical list of restricted cells that the handset 10 haspreviously successfully connected to even though they did not appear inthe “operator controlled CSG list”.

An important aspect of the illustrated embodiment of the presentinvention is the use of signaling arising between the Access Stratum(AS) and Non-Access Stratum (NAS) of the protocol stack within thehandset 10 and which respective layers 22, 24 are also illustratedschematically within FIG. 1.

As is discussed in further detail in relation to FIGS. 2 and 3 below,the NAS layer 24 is arranged to receive signaling in accordance with thepresent invention from the USIM 20 and to interact with the AS layer 22.

Central to the illustrated embodiments of the present invention is theprovision of a CSG whitelist preferably within volatile memory of thehandset 10 and which whitelist can be configured in signaling arisingbetween the AS 22 and the NAS 24 layers within the handset 10.

Advantageously, at most one user-selected CSG identity within the CSGwhitelist is employed and, as discussed below, the required control ofthe CSG whitelist can advantageously be achieved by way of the NAS orindeed the AS.

The further illustration of embodiments of the present inventionprovided by FIGS. 2 and 3 relate respectively to a NAS-controlled CSGwhitelist, and an AS-controlled CSG whitelist.

Although discussed in further detail below it should be appreciatedthat, with the NAS 24 controlling the CSG whitelist, it is apparent thatthe AS does not have nor receive any indication as to whether the“allowed CSG list” is being inhibited by the network or not.

However, whenever the handset 10 moves to a non-CSG cell, or indeed to acell belonging to a different CSG cell (neither of which belong to the“operator controlled CSG list” the NAS layers are advantageouslyarranged to remove the previous user CSG identity from the CSGwhitelist. Further, the NAS layer can also be arranged to notify theupdated CSG whitelist (i.e. the list with the aforementioned “previoususer CSG identity” removed) to the AS layer 22.

As an alternative arrangement for the present invention, and in whichthe AS-controlled CSG whitelist is provided, the AS can be provided withan indication as to whether the “allowed CSG list” has been inhibited ornot by the network and on the basis of an indication provided by theNAS. Again making reference to movement of the handset 10 to a non-CSGcell, or indeed to a cell belonging to a different CSG (both which againare not found within the “operator controlled CSG list”) the AS 22serves to remove the previous user CSG identity from the CSG whitelist.

Thus, with regard to both scenarios above, it will be appreciated thatthe advantageous operation of the present invention, and the limitationsfound within the prior art, can be achieved through simple handling ofat most one user CSG identity within the CSG whitelist.

The invention provides a means for, the UE to achieve inhibition of the“allowed CSG list” in, for example, the ME and, as noted, by handling atmost one user CSG identity. Turning now to a more detailed discussion ofexamples of signaling arrangements according to the embodiments of thepresent invention, reference is made to FIGS. 1 and 2. As noted above,FIG. 1 illustrates an example of the present invention employing aNAS-controlled CSG whitelist, whereas FIG. 2 provides illustration of anexample employing an AS-controlled CSG white list.

Where appropriate, like reference numerals are used in both drawings asare the following CSG related acronyms.

ACL: This relates to the Allowed CSG List and which comprises a list of“user controlled” CSG identities and there respective HMD name if anyand so relate to the “allowed CSG list” discussed above.

OCL: This identifies an Operator CSG List which comprises a list of“operator controlled CSG identities” and the respective HMB name if anyand, as discussed above, comprises the list of CSG IDs relating to therestricted cells to which access is allowed by the Operator.

CSG whitelist: As used with reference to FIGS. 2 and 3 and indeedthroughout the present application, this signifies an internal list ofCSG identities between the NAS and AS within the handset 10 and whichlist contains the sum of the CSG IDs of the ACL and the OCL.

Turning first to FIG. 2 there is provided a signaling diagram arising inrelation to UE in the form of mobile phone handset 10 including the USIM20, AS 22 and NAS 24 also illustrated schematically in FIG. 1. Tocomplete the potential signaling path, a network node 28 and the relatedcore network 30 are also illustrated in FIG. 2 as indeed is referencedto a user 26 selectively operating the UE 10.

It should be appreciated that the aspect of the embodiment of thepresent invention illustrated in FIG. 2 relates to the provision of aNAS-controlled CSG whitelist

Referring to the signaling in turn, within the UE 10, the USIM 20provides USIM CSG information signaling to the NAS 24 and at whichconfirms inhibition of the ACL.

Signaling comprising the configured CSG white list is then deliveredfrom the NAS 24 to the AS 22 and the procedure then follows a pathinvolving manual CSG selection by the use of 26, i.e., in an attempt toconnect to a restricted cell not identified in the “operator controlledCSG list”.

In step 2A, the AS 22 provides for a list of broadcast CSG IDs which, asillustrated, can be delivered to the user 26 for display as appropriate.The list of broadcast CSG IDs may contain CSG IDs not pertaining to theOCL. In step 2B, the list of broadcast CSG IDs is displayed to the user26. From reference to the list, the user can select a CSG ID which isnot found within the OCL in step 2C and signaling relating to thatselection is delivered to the NAS 24 and subsequently the AS 22 whereinthe requested CSG ID is selected in step 2D. Ongoing network signalingis then delivered to the network node 28 and into the core network 30,and from which NAS registration confirmation signaling concerning theselected CSG ID is returned.

Further signaling between the NAS 24 and AS 22 in step 2E relates to afurther configuration of the CSG white list which now includes therecently selected CSG ID.

The particular aspects of the illustrated embodiment of the presentinvention of FIG. 2 are now apparent from the subsequent signaling andfollowing description which can relate to either a cell (re)selection toa non-CSG cell, or indeed to another CSG cell having another CSG IDmanually selected by the user 26.

Cell indication signaling is returned from the AS 22 to the NAS 24 andwhich, as noted, serves to identify a non-CSG cell, or indeed a new CSGID to which connection can be made in view of the apparent failure(perhaps for signal strength/quality reasons) to connect to the newlyselected CSG. In case of new user CSG ID, the steps from “User manualCSG selection” apply here and are not mentioned again to overloadingscenario in step 2F. Upon receipt of that signaling in step 2F, the NAS24 is arranged to add, if appropriate, the new user CSG ID to the CSGwhite list although, subsequently, in accordance with the presentinvention, the CSG white list returned from the NAS 24 has had theprevious user CSG identity removed and, further, the NAS 24 can bearranged to notify the duly further updated CSG white list to the ASlayer 22 in step 2G.

As will be appreciated, upon outbound mobility to a non-CSG cell, theNAS 24 removes the previous user CSG ID from the CSG white list in step2G. However, upon outward mobility to a CSG cell having another user CSGidentity different from the previous user CSG identity, the NAS 24supersedes the previous CSG identity with the new user CSG identitywithin the CSG white list.

Turning now to FIG. 3, there is provided a similar timing diagram tothat of FIG. 2 and involved in the same handset 10 and associated USIM20, NAS 24 and AS 22, network node 28 and core network 30 and similaruser 26. As will be appreciated, FIG. 3 relates to an embodiment inwhich the CSG white list is AS-controlled and, within the initial CSGwhite list signaling from the NAS 24 to the AS 22, there is provided anindication from the NAS 24 that the user controlled CSG selection i.e.that illustrated by the “allowed CSG list” is to be inhibited in step 3Aand the CSG white list and its cells will be stored at the AS 22 in step3B for use in the subsequent cell (re)selection procedure.

A manual user CSG selection procedure in steps 3C to 3F then continuesin the same manner as in relation to FIG. 2, concluding with an NASregistration confirmation having regard to the selected CSG ID deliveredfrom the core network 30 and via the network node 28 to the NAS layer24.

Within the final (re)selection procedure either to a non-CSG cell, or toanother CSG cell having a different CSG ID manually selected by theuser, cell indication signaling is delivered from the AS layer 22 to theNAS layer 24 in accordance with specific features of the presentinvention. The cell indication comprises a non-CSG cell, or new CSG cellID and, in the case of the former, the AS 22 removes the previous userCSG identity from the CSG white list in step 3G. In the case of thelatter, however, the AS 22 supersedes the previous user CSG identitywith the new identity in the CSG white list in step 3G. In the NAS 24,in case of new user CSG ID, the steps from “User manual CSG selection”apply here and are not mentioned again to avoid overloading scenario instep 3H.

It should of course be appreciated that the invention is not restrictedto the details of the forgoing embodiment and in particular, the exactsignaling arrangements illustrated in relation to FIGS. 2 and 3 norindeed the hardware embodiment illustrated with reference to FIG. 1.

INDUSTRIAL APPLICABILITY

The present invention can be applied to a mobile radio communicationsdevice arranged particularly for Closed Subscriber Group (CSG)functionality. According to the present invention, a user can readilyavoid a need to repeat a manual CSG selection procedure when movingbetween cells covered by the same CSG and non-CSG cells in particular.

What is claimed is:
 1. A method performed by a mobile radiocommunications device, the method comprising: retrieving, from aUniversal Subscriber Identity Module (USIM), at least one of an Allowedclosed subscriber group (CSG) list and an Operator CSG list; displaying,to a user, at least one available CSG for a manual CSG selection;providing a CSG whitelist from a non-access stratum layer (NAS) to anaccess stratum layer (AS) within the mobile radio communications device;providing, from the NAS to the AS, an updated CSG whitelist in responseto the contents of the CSG whitelist being changed; and adding a CSGidentity to the Allowed CSG list in response to a registration attemptto a cell of the CSG selected by the manual CSG selection beingaccepted.
 2. A method according to the claim 1, wherein the CSGwhitelist is based on the Allowed CSG list and the Operator CSG list. 3.A method according to the claim 1, wherein the CSG identity is added tothe Allowed CSG list unless the CSG identity is already present in theAllowed CSG.
 4. A mobile radio communications device comprising: atleast one processor configured to: retrieve, from a Universal SubscriberIdentity Module (USIM), at least one of an Allowed closed subscribergroup (CSG) list and an Operator CSG list; display, to a user, at leastone available CSG for a manual CSG selection; provide a CSG whitelistfrom a non-access stratum layer (NAS) to an access stratum layer (AS)within the mobile radio communications device; provide, from the NAS tothe AS, an updated CSG whitelist in response to the contents of the CSGwhitelist being changed; and add a CSG identity to the Allowed CSG listin response to a registration attempt to a cell of the CSG selected bythe manual CSG selection being accepted.
 5. A mobile radiocommunications device according to the claim 4, wherein the CSGwhitelist is based on the Allowed CSG list and the Operator CSG list. 6.A mobile radio communications device according to the claim 4, whereinthe CSG identity is added to the Allowed CSG list unless the CSGidentity is already present in the Allowed CSG.